/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.lucene.analysis.wikipedia;
import org.apache.lucene.analysis.Tokenizer;
import org.apache.lucene.analysis.tokenattributes.CharTermAttribute;
import org.apache.lucene.analysis.tokenattributes.FlagsAttribute;
import org.apache.lucene.analysis.tokenattributes.OffsetAttribute;
import org.apache.lucene.analysis.tokenattributes.PositionIncrementAttribute;
import org.apache.lucene.analysis.tokenattributes.TypeAttribute;
import org.apache.lucene.util.AttributeSource;
import java.io.IOException;
import java.io.Reader;
import java.util.*;
/**
* Extension of StandardTokenizer that is aware of Wikipedia syntax. It is based off of the
* Wikipedia tutorial available at http://en.wikipedia.org/wiki/Wikipedia:Tutorial, but it may not be complete.
* <p/>
* <p/>
* @lucene.experimental
*/
public final class WikipediaTokenizer extends Tokenizer {
public static final String INTERNAL_LINK = "il";
public static final String EXTERNAL_LINK = "el";
//The URL part of the link, i.e. the first token
public static final String EXTERNAL_LINK_URL = "elu";
public static final String CITATION = "ci";
public static final String CATEGORY = "c";
public static final String BOLD = "b";
public static final String ITALICS = "i";
public static final String BOLD_ITALICS = "bi";
public static final String HEADING = "h";
public static final String SUB_HEADING = "sh";
public static final int ALPHANUM_ID = 0;
public static final int APOSTROPHE_ID = 1;
public static final int ACRONYM_ID = 2;
public static final int COMPANY_ID = 3;
public static final int EMAIL_ID = 4;
public static final int HOST_ID = 5;
public static final int NUM_ID = 6;
public static final int CJ_ID = 7;
public static final int INTERNAL_LINK_ID = 8;
public static final int EXTERNAL_LINK_ID = 9;
public static final int CITATION_ID = 10;
public static final int CATEGORY_ID = 11;
public static final int BOLD_ID = 12;
public static final int ITALICS_ID = 13;
public static final int BOLD_ITALICS_ID = 14;
public static final int HEADING_ID = 15;
public static final int SUB_HEADING_ID = 16;
public static final int EXTERNAL_LINK_URL_ID = 17;
/** String token types that correspond to token type int constants */
public static final String [] TOKEN_TYPES = new String [] {
"<ALPHANUM>",
"<APOSTROPHE>",
"<ACRONYM>",
"<COMPANY>",
"<EMAIL>",
"<HOST>",
"<NUM>",
"<CJ>",
INTERNAL_LINK,
EXTERNAL_LINK,
CITATION,
CATEGORY,
BOLD,
ITALICS,
BOLD_ITALICS,
HEADING,
SUB_HEADING,
EXTERNAL_LINK_URL
};
/**
* Only output tokens
*/
public static final int TOKENS_ONLY = 0;
/**
* Only output untokenized tokens, which are tokens that would normally be split into several tokens
*/
public static final int UNTOKENIZED_ONLY = 1;
/**
* Output the both the untokenized token and the splits
*/
public static final int BOTH = 2;
/**
* This flag is used to indicate that the produced "Token" would, if {@link #TOKENS_ONLY} was used, produce multiple tokens.
*/
public static final int UNTOKENIZED_TOKEN_FLAG = 1;
/**
* A private instance of the JFlex-constructed scanner
*/
private final WikipediaTokenizerImpl scanner;
private int tokenOutput = TOKENS_ONLY;
private Set<String> untokenizedTypes = Collections.emptySet();
private Iterator<AttributeSource.State> tokens = null;
private final OffsetAttribute offsetAtt = addAttribute(OffsetAttribute.class);
private final TypeAttribute typeAtt = addAttribute(TypeAttribute.class);
private final PositionIncrementAttribute posIncrAtt = addAttribute(PositionIncrementAttribute.class);
private final CharTermAttribute termAtt = addAttribute(CharTermAttribute.class);
private final FlagsAttribute flagsAtt = addAttribute(FlagsAttribute.class);
/**
* Creates a new instance of the {@link WikipediaTokenizer}. Attaches the
* <code>input</code> to a newly created JFlex scanner.
*
* @param input The Input Reader
*/
public WikipediaTokenizer(Reader input) {
this(input, TOKENS_ONLY, Collections.<String>emptySet());
}
/**
* Creates a new instance of the {@link org.apache.lucene.analysis.wikipedia.WikipediaTokenizer}. Attaches the
* <code>input</code> to a the newly created JFlex scanner.
*
* @param input The input
* @param tokenOutput One of {@link #TOKENS_ONLY}, {@link #UNTOKENIZED_ONLY}, {@link #BOTH}
* @param untokenizedTypes
*/
public WikipediaTokenizer(Reader input, int tokenOutput, Set<String> untokenizedTypes) {
super(input);
this.scanner = new WikipediaTokenizerImpl(input);
init(tokenOutput, untokenizedTypes);
}
/**
* Creates a new instance of the {@link org.apache.lucene.analysis.wikipedia.WikipediaTokenizer}. Attaches the
* <code>input</code> to a the newly created JFlex scanner. Uses the given {@link org.apache.lucene.util.AttributeSource.AttributeFactory}.
*
* @param input The input
* @param tokenOutput One of {@link #TOKENS_ONLY}, {@link #UNTOKENIZED_ONLY}, {@link #BOTH}
* @param untokenizedTypes
*/
public WikipediaTokenizer(AttributeFactory factory, Reader input, int tokenOutput, Set<String> untokenizedTypes) {
super(factory, input);
this.scanner = new WikipediaTokenizerImpl(input);
init(tokenOutput, untokenizedTypes);
}
/**
* Creates a new instance of the {@link org.apache.lucene.analysis.wikipedia.WikipediaTokenizer}. Attaches the
* <code>input</code> to a the newly created JFlex scanner. Uses the given {@link AttributeSource}.
*
* @param input The input
* @param tokenOutput One of {@link #TOKENS_ONLY}, {@link #UNTOKENIZED_ONLY}, {@link #BOTH}
* @param untokenizedTypes
*/
public WikipediaTokenizer(AttributeSource source, Reader input, int tokenOutput, Set<String> untokenizedTypes) {
super(source, input);
this.scanner = new WikipediaTokenizerImpl(input);
init(tokenOutput, untokenizedTypes);
}
private void init(int tokenOutput, Set<String> untokenizedTypes) {
this.tokenOutput = tokenOutput;
this.untokenizedTypes = untokenizedTypes;
}
/*
* (non-Javadoc)
*
* @see org.apache.lucene.analysis.TokenStream#next()
*/
@Override
public final boolean incrementToken() throws IOException {
if (tokens != null && tokens.hasNext()){
AttributeSource.State state = tokens.next();
restoreState(state);
return true;
}
clearAttributes();
int tokenType = scanner.getNextToken();
if (tokenType == WikipediaTokenizerImpl.YYEOF) {
return false;
}
String type = WikipediaTokenizerImpl.TOKEN_TYPES[tokenType];
if (tokenOutput == TOKENS_ONLY || untokenizedTypes.contains(type) == false){
setupToken();
} else if (tokenOutput == UNTOKENIZED_ONLY && untokenizedTypes.contains(type) == true){
collapseTokens(tokenType);
}
else if (tokenOutput == BOTH){
//collapse into a single token, add it to tokens AND output the individual tokens
//output the untokenized Token first
collapseAndSaveTokens(tokenType, type);
}
posIncrAtt.setPositionIncrement(scanner.getPositionIncrement());
typeAtt.setType(type);
return true;
}
private void collapseAndSaveTokens(int tokenType, String type) throws IOException {
//collapse
StringBuilder buffer = new StringBuilder(32);
int numAdded = scanner.setText(buffer);
//TODO: how to know how much whitespace to add
int theStart = scanner.yychar();
int lastPos = theStart + numAdded;
int tmpTokType;
int numSeen = 0;
List<AttributeSource.State> tmp = new ArrayList<AttributeSource.State>();
setupSavedToken(0, type);
tmp.add(captureState());
//while we can get a token and that token is the same type and we have not transitioned to a new wiki-item of the same type
while ((tmpTokType = scanner.getNextToken()) != WikipediaTokenizerImpl.YYEOF && tmpTokType == tokenType && scanner.getNumWikiTokensSeen() > numSeen){
int currPos = scanner.yychar();
//append whitespace
for (int i = 0; i < (currPos - lastPos); i++){
buffer.append(' ');
}
numAdded = scanner.setText(buffer);
setupSavedToken(scanner.getPositionIncrement(), type);
tmp.add(captureState());
numSeen++;
lastPos = currPos + numAdded;
}
//trim the buffer
// TODO: this is inefficient
String s = buffer.toString().trim();
termAtt.setEmpty().append(s);
offsetAtt.setOffset(correctOffset(theStart), correctOffset(theStart + s.length()));
flagsAtt.setFlags(UNTOKENIZED_TOKEN_FLAG);
//The way the loop is written, we will have proceeded to the next token. We need to pushback the scanner to lastPos
if (tmpTokType != WikipediaTokenizerImpl.YYEOF){
scanner.yypushback(scanner.yylength());
}
tokens = tmp.iterator();
}
private void setupSavedToken(int positionInc, String type){
setupToken();
posIncrAtt.setPositionIncrement(positionInc);
typeAtt.setType(type);
}
private void collapseTokens(int tokenType) throws IOException {
//collapse
StringBuilder buffer = new StringBuilder(32);
int numAdded = scanner.setText(buffer);
//TODO: how to know how much whitespace to add
int theStart = scanner.yychar();
int lastPos = theStart + numAdded;
int tmpTokType;
int numSeen = 0;
//while we can get a token and that token is the same type and we have not transitioned to a new wiki-item of the same type
while ((tmpTokType = scanner.getNextToken()) != WikipediaTokenizerImpl.YYEOF && tmpTokType == tokenType && scanner.getNumWikiTokensSeen() > numSeen){
int currPos = scanner.yychar();
//append whitespace
for (int i = 0; i < (currPos - lastPos); i++){
buffer.append(' ');
}
numAdded = scanner.setText(buffer);
numSeen++;
lastPos = currPos + numAdded;
}
//trim the buffer
// TODO: this is inefficient
String s = buffer.toString().trim();
termAtt.setEmpty().append(s);
offsetAtt.setOffset(correctOffset(theStart), correctOffset(theStart + s.length()));
flagsAtt.setFlags(UNTOKENIZED_TOKEN_FLAG);
//The way the loop is written, we will have proceeded to the next token. We need to pushback the scanner to lastPos
if (tmpTokType != WikipediaTokenizerImpl.YYEOF){
scanner.yypushback(scanner.yylength());
} else {
tokens = null;
}
}
private void setupToken() {
scanner.getText(termAtt);
final int start = scanner.yychar();
offsetAtt.setOffset(correctOffset(start), correctOffset(start + termAtt.length()));
}
/*
* (non-Javadoc)
*
* @see org.apache.lucene.analysis.TokenStream#reset()
*/
@Override
public void reset() throws IOException {
super.reset();
scanner.yyreset(input);
}
@Override
public void reset(Reader reader) throws IOException {
super.reset(reader);
reset();
}
@Override
public void end() throws IOException {
// set final offset
final int finalOffset = correctOffset(scanner.yychar() + scanner.yylength());
this.offsetAtt.setOffset(finalOffset, finalOffset);
}
}